Screen assembly



July 15, 1969 F. M. LE TARTE 3,455,367

' SCREEN ASSEMBLY Filed June 14, 1967 2 Sheets-Sheet l INVENTOR. .FPANKM. 1172mm:

F. M. LE TARTE SCREEN ASSEMBLY July 15, 1969 2 Sheets-Sheet 2 Filed June14, 1967 m 6G R. ME O SON M M ,3 A E s w W4 5 M L 7 H F W Um o A 0 0 d WM Y u B 0 L 0 United States Patent 3,455,367 SCREEN ASSEMBLY Frank M. LeTarte, P.0. Box 68, Smith Creek, Mich. 48074 Filed June 14, 1967, Ser.No. 646,013 Int. Cl. A47g /00; A47h 13/00 US. Cl. 160371 6 ClaimsABSTRACT OF THE DISCLOSURE BRIEF DESCRIPTION OF THE INVENTION Briefly, aprecut section of screening material of the approximate size of a screenframe ismounted in a screen frame by tucking the edges of the screenmaterial into a recess or channel of the metal frame member, thuseliminating the labor involved in trimming and/or dressing the screenmaterial to a specific size. The term approximate size refers to ascreen material having dimensions of the order of i625 inches relativeto a predetermined line at or near the centerline of the frame member.The next steps are to melt a portion of the thermoplastic strip andpress the screen into softened plastic. U

It is an object of this invention to provide an inexpensive frameconstruction that increases the structural rigidity of thethermoplastic-metal extrusion combination.

Another object of this invention is provision of a method for mounting aprecut section of screen on the frame which is more economical andsimpler than methods known in the art because it eliminates the stepBRIEF DESCRIPTION OF THE DILAWINGS FIGURE 1 is a perspective view of acompleted screen assembly made in accordance with this invention;

FIGURE 2 is a cross-sectional 'view, to a greatly enlarged scale, of thethermoplastic strip of FIGURE l;

FIGURE 3 is a cross-sectional view, to a greatly enlarged scale, takenalong the line 33 of FIGURE 1, of the U-shaped extruded metal framestrip with the dashed line indicating the position of the thermoplasticstrip in the complete frame assembly;

FIGURE 4 is a view of the assembled screen showing the frame, plasticstrip, screening material and assembling tool;

FIGURE 5A is a cross-sectional view of the metal frame and showing theposition of the tool in fabricating the completed screen assembly with acutaway view of the roller showing a Teflon or similar material coatedon the metal roller;

FIGURE 5B is a fragmentary side view of FIGURE 5A looking in thedirection of arrow 5B; and

FIGURE 6 is a cross-sectional view of the completed frame assembly, toan enlarged scale, taken along the the arrows.

2 DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawing, ascreen 10 is secured to a rigid metal frame 11 by means of an elongatedthermoplastic strip 12.. Frame 10 may be formed from a notched singlepiece metal extrusion as disclosed in my patent No. 3,097,684. Thecomplete assembly is shown in perspective in FIGURE 1. The structuraldetails, the manner of assembly of the plastic and metal-strips, and themounting of the frame aredescribed in conjunction with FIGURES 2 through6. FIGURES 2 and 3 are views in section, to a greatly enlarged scale, ofthe plastic strip 12 and frame 11, which is advantageously: formed froma generally U-shaped metal extrusion.

Frame 11 and strip 12 are each cut to a predetermined length. The frame11 is preferably formed by notching the elongated metal with fournotches toeleave' one uncut extrusion wall at each notch. Corners areformed by bending each uncut wall of the extrusion at each notch andjoining the ends of the extrusion by means-of a gusset 13. The cornermay be strengthened by welding the abutting edges of each notch. Thegusset is preferably secured to the extrusion 11 by means of spotwelding, as I each length of frame section. The plastic strip issnapped'into place in the channel of the frame 11 in a manner shown in dottedoutline in FIGURE 3. Alternatively, a single length of plastic equal tothe perimeter of frame 11 may be snapped into the metal channel memberbefore the channel member is notched. The stripwill then be mitered infour segments. The mitered ends will abut each other when the frame isbent at the notches.

Strip 12 is preferably formed of any convenient thermoplastic material,such as Cycloac, which is sold by Marbon Chemical Div. This material isa styrene-type, rigid, thermoplastic resin which softens gradually asthe temperature is increased beyond 185 F. The-particular strip 12includes a main body portion 15 from which three longitudinal ridges 16pr0ject.-A longitudinal tongue or lip 18 projects from the main bodyportion 15 at an angle of relative to ridges 16 and secures one edge ofstrip 12 in frame 11, as will be subsequently described.

The plastic strip 12 also includes, as viewed in section in FIGURE 2, aleg 23 depending from the main body portion 15 and having three portions24, 25 and 26. These portions are integrally formed with each other andwith main body portion 15. Portions 24, 25 and 26 preferably define aseries of right angles. Leg 23 terminates in a foot 28, and leg 23 hassufficient resilience so that the foot 28 can snap into a slot in themetal extrusion to lock the strip in the metal frame in a manner to bedescribed.

Frame 11 is preferably formed from a soft metal extrusion 20, such asaluminum. Extrusion 20 includes a base portion 29 and a pair of arms 30,31 extending substantially perpendicularly from base 29. Arms 30 and 31define the inner and outer walls, respectively, of the frame. A ledge orlip 32 projects toward the outer wall 31 from the end of inner wall 30.A relatively wide lip 34 projects perpendicularly from wall 31'towardwall 30. A tongue or shelf 35 projects perpendicularly from the insidewall 31. Shelf 35 supports plastic strip 12 in a manner shown in phantomoutline in FIGURE 3 and shown in full lines in FIGURES 4, 5 and 6. Inassembling the plastic strip on shelf 35, the plastic strip is firstmoved in the channel of member 20 in the direction of arrow 36. Afterleg 23 passes shelf 35, the plastic strip is moved in the direction ofarrow 37 until lip 18 engages the inner surface of wall 30 and the innersurface of ledge 32 and until the foot 28 snaps into a longitudinalgroove 40. Member 20 also includes a pair of opposed ridges 38, 39 Ridge39 projects perpendicularly from base 29 toward top ledge 34. Ridges 38and 39 and wall 31 define a substantially enclosed rectangular channelto receive gusset 13.

The engagement of foot 28 in a groove 40 in base portion 29 preventsmovement of the thermoplastic strip 12 in the plane of the base 29 in adirection opposite to arrow 37. The motion of strip 12 in a directionopposite to arrow 36 (as might be otherwise produced by pressure uponscreen 10 in a direction upward, as viewed in FIGURES 3 and 6) isprevented by the engagement of tongue 18 with the inside surface ofledge or lip 32 and the engagement of leg 25 with the lower surface ofshelf 35.

After the plastic strip 12 is mounted in the frame 11, a precut area ofscreen 10 is placed upon the frame and strip with the edges of thescreen overlapping the plastic strip in a manner shown in FIGURE 4.Screen 10 may be of conventional metal such as aluminum or it may beformed of suitable thermoplastic material. Roller 41 may be heated, aswill be subsequently described, or heat sufficient to soften strip 12and screen 10 may be provided in the form of a hot gaseous blast from asuitable nozzle 42. The overlapping edges of the screen are tucked intothe channel of the frame member 20, as shown in FIG- URES 3 and 6. Thelongitudinal ridges 16 are subsequently melted and the screen is pressedinto the softened plastic material by means of a single tool, such asthe roller 41. By using precut screen sections, a substantial savings(approximately 25%) is obtained in the purchase price of screen, whenscreen is sold in rolls, and a portion of the roll is damaged duringproduction or handling. The roll cannot be sold hence an appreciableloss occurs. However, if screen is purchased in precut, fiat sections,only the damaged sections need be returned. Further, fiat sections maybe palletized to facilitate handling without damage.

Roller 41 is rotatably mounted on a suitable bifurcated handle 44 by anaxel 45, journaled in the bifurcated portion bf the handle 44. Theroller 41 is preferably electrically heated by passing an electricalcurrent through a resistive material 48 beneath the Teflon coating 49 ofthe roller 41. Contacts 46 and 47, appearing on the lefthand fork of thebifurcated handle 44, as viewed in FIGURE 4, provide a means forconducting electrical current to the resistive coating on roller 41.Resistive coating 48, shown in FIGURE 5, is preferably covered bya,Tefion or other suitable coating 49, which Teflon coating prevents theheat softened plastic material of the plastic strip 12 and/or screen 10from adhering to the roller 41.

FIGURES A and 5B show the melting and fusing of the longitudinal ridges16 into the screen 10. As best shown in FIGURES 5A and 5B, the roller 41rests upon the outer top ledge or rail 34, which rail projects above theinner rail 32 to act as a gauge to limit the amount of pressure and thedepth of penetration of the roller 41 into the longitudinal ridges 16.After the roller 41 is passed along two adjoining sides of the frame 11,a suitable tool, not shown, preferably having the saw-tooth end, isinserted into the screen adjacent the channel at the corner diagonallyopposite the corner connecting the two portions of the strip 12 to whichthe screen has been fastened. By applying pressure at this diagonallyopposite corner, any sag is removed from the screen and the heatedroller or roller and hot gas tube 42 may be passed along the tworemaining sides of the plastic strip 12 to thus complete the mounting ofthe screen on the plastic strip 12.

The structural details of the resulting junction of the screen andplastic strip are best shown in FIGURE 6 which is similar to FIGURE 5Aexcept that the roller 41 has been removed. The pre-cut screen 10 hasbeen bonded to the longitudinal ridges 16 of the strip 12, as best seenin FIGURE 6.

Typical dimensions for the channel member 20, expressed in inches, areas follows:

Wall 30 0.245 Base 29 0.750 Wall 31 0.275 Inner ledge 32 0.093 Outerledge 34 0.312

The width of shelf 35, measured from the outside of wall 30, is 0.280while the height of the gusset channel, formed by the opposed arms 30,31, is 0.185. The groove 40 is of the order of 0.040 in Width and 0.015in depth. Strip 12 may be relatively rigid, such as being within therange of 65 to on the D scale, as measured on a Shore Durometer. Typicaldimensions for a strip 12, in inches, are:

Width of body 15 .225 Height of body 15 .070 Overall height .250 Overallwidth .270 Width of ridges 16 .045 Width of tongue 18 .045

In summary, structural rigidity is accomplished by means of a designwhich prohibits motion of the thermoplastic in any direction in which atension on the screening material could force it to move, whileincreasing the economy of construction by eliminating the necessity fortrimming the screening material. In particular, a novel feature includesthe engagement of foot 28 with groove 40 for prohibiting movement of thethermoplastic away from sidewall 30 of the U shaped extrusion 20 withoutincreasing the complexity of the construction. Also, the engagement oftongue 18 under shelf 32 prevents strip 12 from being pulled out whenpressure is applied to the screen 10 upwardly, as viewed in FIGURES 3and 6.

In accordance with the patent statutes, the principles of the presentinvention may be utilized in various ways, numerous modifications andalterations being contemplated, substitution of parts and changes inconstruction being resorted to as desired, it being understood that theembodiment shown in the drawing is given merely for purposes ofexplanation and illustration without intending to limit the scope of theclaims to the specific details disclosed. For example, the step ofheating the plastic strip and the plastic screen may be performed bydielectric high frequency heating. In this manner, the roller acts asone electrode and the screen frame acts as the other electrode when ahigh frequency signal is applied to these electrodes.

I claim:

1. A screen assembly comprising:

a polygonal frame formed of a substantially U shaped channel memberhaving in cross-section a base portion,

a pair of arms extending from said base portion and a longitudinal shelfextending from one arm toward the other arm,

an elongated thremoplastic strip having a longitudinal slot therein saidstrip being mounted in said channel with said shelf extending into saidslot, and

a screen member, said thermoplastic strip being fused around said screenmember.

2. A screen assembly according to claim 1 wherein said channel memberincludes means for retaining said strip on said shelf.

3. A screen assembly according to claim 1 wherein said shelf extendsfrom the inner wall of said frame toward the outer wall of said frameand wherein said channel member includes means for preventing movementof said strip transversely relative to said shelf.

4. A screen assembly according to claim 3 wherein said channel memberhas a longitudinal ledge projecting from the end of one arm toward theother arm and wherein the edge of said screen projects into said channelmember and beneath said ledge, said one arm being longer ReferencesCited stag; said other arm to act as gauge for said thermoplastic UNITEDSTATES PATENTS 5. A screen assembly according to claim 1 wherein1,794,956 3/1931 Heath 160 "395 said frame includes a lip projectingfrom one of said 5 2,126,544 8/1938 Everhal'd 160 395X arms toward theother of said arms and wherein said 2,325,500 7/1943 FosPerg 16O 383plastic strip includes a longitudinally extending tongue 2,335,36111/1943 Schlner 16O395 portion extending beneath said lip whereby saidlip pre- 2,783,834 3/1957 Brame 160 395 vents said screen from pullingsaid strip from said shelf 3,097,684 7/1963 Le Tarte 160381 X whenpressure is applied to said screen. 3,214,314 10/1965 ROW Bottam 160 371X 6. A screen assembly according to claim 5 10 3,273,633 9/1966 Seidmonet wherein said tongue portion is positioned between said shelf and saidlip and REINALDO P. MACHADO, Primary Examiner wherein said channelmember includes a locking groove P. C. KANNAN, Assistant Examiner facingsaid shelf and opposed thereto, said strip in- 15 eluding a portionprojecting into said groove to retain US. Cl- X.R.

said strip on said shelf. 160383, 395

